Observations on some species of Orina. 17 



breaks through the incisions of the segments with a raised 

 ridge, and leaves the sides below it somewhat flat down to 

 the marginal flange ; whilst in the other species the back 

 is regularly arched across from the marginal flange, and 

 there is no continuity of the subdorsal flange across the 

 incisions. 



This species feeds openly in contrast to the hiding 

 habits of 0. vittigera, so that one suspects the brilliant 

 contrast of yellow and black in its coloration to be 

 probably of a warning character. 



0. gloriosa is of a pale nankeen colour, very different to 

 the dark sepia colour of 0. vittigera and 0. tristis, and 

 has a definite fold in the subsegmental incisions, that is 

 less pronounced than in 0. vittigera, and of a somewhat 

 different character. 



0. tristis when full-grown approaches very closely to 0. 

 vittigera, but is more densely dark, and has a different 

 fold in the subsegmental incision to both 0. vittigera and 

 0. gloriosa. It agrees with 0. cacalis& in feeding on Com- 

 posite and not on Umbelliferze as 0. vittigera and 0. gloriosa 

 do, but structurally its alliance is much more with the 

 latter. 



The points which seem to be most noteworthy in our 

 observations are in confirming the viviparity of the genus 

 and in finding one species that is not strictly viviparous. 

 The observation that the eggs develop into larvae in the 

 ovarian tubules is a very unexpected one, and suggests 

 further researches, which should disclose various points of 

 difference from the usual method of fecundation of the ova 

 in insects. The larvae of 0. tristis and 0. vittigera do not 

 appear to have been previously described, nor of course 

 brought together alive for comparison with the other 

 species. 



Explanation of Plates I. and II. 



[See next page.] 



TRANS. ENT. SOC. LOND. 1901. — PART I. ( APRIL) 2 



